The present invention is directed to an internal combustion engine.
An internal combustion engine referred to in German Published Patent Application No. 198 26 074 includes an electrohydraulic valve control device, including valve actuators configured as hydraulic actuators, each of these actuating one of the gas-exchange valves. Each hydraulic actuator may have a double-acting working cylinder in which an operating piston may be guided in an axially displaceable manner. The operating piston may be rigidly connected to a piston rod, which may be guided out of the working cylinder and, itself, may be rigidly connected to the valve tappet of a gas-exchange valve or may be formed in one piece with it.
An exemplary internal combustion engine according to the present invention may provide two gas-exchange valves that are operated using a single valve actuator. In this context, the closing and opening of both gas-exchange valves may be reliably ensured, regardless of any existing component tolerances. In particular, it may be ensured that the valve elements of both gas-exchange valves in the valve closed position tightly abut the valve seat, so that the combustion chamber of the combustion cylinder may be reliably sealed. By economizing one valve actuator per combustion cylinder, the manufacturing costs for the internal combustion engine""s valve control device may be reduced.
According to one exemplary embodiment of the present invention, the valve actuator may have a double-acting hydraulic working cylinder, including an operating piston that may be guided in the working cylinder in an axially displaceable manner, as well as a piston rod that may be rigidly connected to the operating piston and led through the working cylinder. The coupling element may be fastened to the piston rod""s rod section which is led through the working cylinder by a swivel bearing, a swiveling axis being oriented transversely to the stroke direction of the operating piston.
The flexible connection sites may be formed so that the gas-exchange valves in the connection sites may perform at least a pendulum motion and a translatory shifting motion in each case relative to the coupling element and transversely to the stroke direction of the operating piston. In the case of two gas-exchange valves actuated by the valve actuator, the connection sites for both gas-exchange valves may be located on the coupling element on both sides of the swivel bearing. This structural configuration may ensure that both gas-exchange valves are reliably closed, even if due to component tolerances and thermal expansions, the valve elements of both gas-exchange valves do not simultaneously place themselves against their associated valve seat in the combustion cylinder.
If the valve element of the one gas-exchange valve abuts on the valve seat, the operating piston may not be blocked in its stroke motion and may move further due to the swivel bearing between the piston rod and coupling element, with result that the coupling element performs a swiveling motion until the valve element of the second gas-exchange valve also abuts the valve seat. In this context, the pendulum and translatory shifting support of the valve stems of both gas-exchange valves in the connection sites may prevent a blockage of the swiveling motion of the coupling element since the coupling element may position itself at an angle with respect to the valve stems without lateral forces being applied to the valve stems.